Call contract read methods from the client

Dev:

Remove calls to API to the following resource: /api/v2/smart-contracts/:hash/methods-read, /api/v2/smart-contracts/:hash/methods-read-proxy, /api/v2/smart-contracts/:hash/query-read-method, /api/v2/smart-contracts/:hash/methods-write, /api/v2/smart-contracts/:hash/methods-write-proxy
Get contract ABI from /api/v2/smart-contracts/:hash and display contract methods in the corresponding tabs; for proxy-contract also requests ABI if its implementation(s)
[x] If there is no public RPC node for a blockchain, the client should make all requests via the Blockscout proxy node (need an example)

Design:

[x] For methods that return a constant value show a "Retry" button when a query fails. Also, add a button to re-request the displayed value.
[x] In the proxy tabs, we need a selector for contract implementations. This will allow users to choose methods from the desired contract.

Testing:

[ ] Deploy a contract where we can test a major part of all corner cases (e.g with complex method arguments structure)

blockscout / frontend